Differential effects of neuropeptides on coeliac and superior mesenteric blood flows in conscious rats.

The effects on coeliac and superior mesenteric blood flows of intravenous bolus doses of arginine-8-vasopressin (0.7 and 7.0 pmol) porcine neuromedin U-25 (0.01 and 1.0 nmol), rat alpha-calcitonin gene-related peptide (0.05 and 0.5 nmol), bombesin (0.06 and 0.6 nmol), and rat corticotropin-releasing factor (1.0 and 5.0 nmol) were investigated in conscious, Long-Evans rats chronically instrumented with pulsed Doppler flow probes. The peptides investigated were chosen on the basis of the range (vasoconstrictor-vasodilator) of their effects on superior mesenteric blood flow. With the exception of rat corticotropin-releasing factor (which increased coeliac and superior mesenteric flows) all peptides caused directionally opposite changes in coeliac and superior mesenteric blood flows. The results are consistent with the proposition that endogenous neuropeptides could influence blood flows to different abdominal viscera selectively.